Bis(2,2,2-trifluoroethyl)ether and method of preparation



United States Patent 3,363,006 BIS (2,2,2-'IRIFLUOROETHYL)ETHER ANDMETHOD OF PREPARATION John F. Olin, Dayton, Ohio, assignor to PennsaltChemicals Corporation, Philadelphia, Pa., a corporation of PennsylvaniaNo Drawing. Continuation of application Ser. No. 556,056, Dec. 29, 1955.This application June 20, 1960, Ser. No. 37,035

' Claims. (Cl. 260-614) ABSTRACT OF THE DISCLOSUREBis(2,2,2-trifluoroethyl) other is prepared by reacting a2,2,2-trifluoroethylate of an alkali metal or alkaline earth metal witha 2,2,2-trifluoroethyl ester of an aromatic sulfonic acid preferably inan organic solvent.

This invention relates to a novel fluorinated alkyl ether and to amethod for its production. More particularly it relates tobis(2,2,2-trifiuoroethyl) ether,

This application is a continuation of Ser. No. 556,056, filed Dec. 29,1955 and now abandoned.

An object of this invention is to prepare the simple ether of2,2,2-trifluoroethanol, i.e., one in which both fiuoroalkyl groups arealike, in this case CF CH Another object is to provide a method for thepreparation of this novel ether.

Conventional methods for the preparation of an alkyl ether from analcohol are (1) to dehydrate the alcohol or (2) to prepare a metalalcoholate and react it with an alkyl halide. However, as is known inthe art, methods useful for the preparation of alkyl compounds are notalways applicable to the preparation of the corresponding fluorinatedalkyl compounds. See, for example, chapter 14, Fluorocarbon Derivatives,in Fluorine Chemistry, by J. H. Simon, vol. I, p. 463-517. Thus,although the bis(2,2,2-trifluoroethyl) ether of this invention isderived indirectly from its corresponding fluoroalcohol,2,2,2-trifiuoroethanol, neither of the above methods is successful forpreparation of this novel ether.

The general procedures used for preparing fluorine-containing ethershave also been found inoperative for the preparation ofbis(2,2,2-trifluoroethyl) ether. These include (1) Exchange fluorinationof chlorineor bromine-containing ethers,

(2) Addition of metal alcoholates to fluorine-containing ethylenes,

(3) Reaction of metal alcoholates with fluorine-containing carbonhalides, and

(4) The electrochemical process using organic ethers.

The fluorinated alcohol, 2,2,2-trifluoroethanol, is uncommonly stable todehydration. It can be heated in concentrated sulfuric acid withoutdehydrating to form an ether. It can also be passed over phosphorouspentoxide at 250 C. with no apparent dehydration occurring.

The sodium salt of 2,2,2-trifluoroethanol is equally highly resistant toreaction with an alkyl halide. For example, mixed ethers of2,2,2-trifluoroethanol have been prepared only under severe conditions,by subjecting sodium 2,2,2-trifluoroethylate with an alkyl halide toelevated temperatures in a pressure bomb for 75 to 125 hours. However,even under similar extreme conditions, the bis(2,2,2-trifluoroethyl)ether is not formed when so dium 2,2,2-t1ifluoroethylate which also canbe called sodium 2,2,2-trifluoroethanolate, is heated at elevatedtemperatures with 2,2,2-trifiuoroethyl chloride or iodide in a pressurere actor.

3,363,006 Patented Jan. 9, 1968 It has now surprisingly been found thatthe novel bis (2,2,2-trifluoroethyl) ether can be made rapidly atatmospheric pressure in an ordinary reactor by reacting the metalfluoroalcoholate of 2,2,2-trifiuoroethanol with the 2,2,2-trifiuoroethylester of an aromatic sulfonic acid at elevated temperatures, recoveringbis(2,2,2-tn'fluoroethyl) ether from the reaction products.

The resulting new chemical compound of my invention,bis(2,2,2-trifluoroethyl) ether, is a colorless liquid which vaporizesreadily at ordinary temperatures and has useful solvent properties. Forexample, it may be used to prepare pastes or dispersions of highmolecular weight fluorine compounds such as fluorocarbon Waxes. It alsomay be used to soften or solubilize polymeric materials, e.g., syntheticfibres. It is chemically reactive and may be used in the preparation ofother fiuorinated compounds.

'The reaction in the process of this invention is represented by thefollowing equation, in which M is an alkali or alkaline-earth metalselected from the group consisting of sodium, potassium, and lithiumalkali metals and barium, calcium and strontium alkaline-earth metals,and R is aryl or substituted-aryl with less than about 20 carbon atoms:

CF CH OCH CF +RS O 0M The metal fluoroalcoholates of2,2,2-trifluoroethanol which are suitable for carrying out the method ofthis invention are selected reactive alkali and alkaline-earth metalfluoroalcoholates. These include the lithium, sodium, and potassiumalkali metal fluoroalcoholates and the barium, calcium and strontiumalkaline-earth metal fluoroalcoholates. The fluoroalcoholate of thesodium metal is preferred.

The metal fluoroalcoholate is prepared as a solution or dispersion,depending on its solubility at the reaction temperature, in an inertliquid reaction medium. The selected reaction medium should be inert tothe action of sodium and the 2,2,2-trifluoroethyl ester of the sulfonicacid being used. Dioxane is the preferred liquid reaction medium. Otherinert organic liquids with sufiiciently high boiling points, e.g. aboveabout C., may also be used, e.g., benzene, toluene, xylene, andkerosene. The weight of liquid reaction medium used is about of thetotal Weight of the metal 2,2,2-trifiuoroethanol solution and about 40%of the total weight of the ether-formation step reaction mass. Theamount used may be varied upward without adversely affecting thepractice of this invention. Use of less liquid reaction medium isfeasible but less advantageous because of the explosive nature of someconcentrated metal 2,2,2-trifluoroethylates at elevated temperatures.

Although the preferred procedures of this invention are carried out inthe presence of an added liquid reaction medium, the process can also becarried out in the absence of such added medium by using instead a largeexcess of 2,2,2-trifluoroethanol.

2,2,2-trifluoroethyl p-toluenesulfonate is the preferred ester for usein the'process of this invention. However, the 2,2,2-trifluoroethylesters of other aromatic sulfonic acids and substituted-aromaticsulfonic acids may be used, e.g., those of benzene-, xylene-,naphthalene-, and anthracenesulfonic acids, and e.g.,dodecylbenzenesulfonic acid, and amylnaphthylenesulfonic acid. Theseesters are readily prepared by reacting the corresponding sulfonylchloride with 2,2,2-trifiuoroethanol by methods known in the art.

The formation of the bis(2,2,2-trifluoroethyl) ether takes place rapidlyand can be carried out in a period of from 60 to 600 minutes. A periodof about 60 to minutes is preferred.

Reaction of the metal 2,2,2-trifiuoroethylate with the2,2,2-trifluoroethyl ester of an aromatic sulfonic acid can be carriedout in the temperature range from about 100 to about 250 C. Thepreferred temperature range is from about 160 to about 185 C.

The metal 2,2,2-trifluoroethylate can be reacted with the2,2,2-trifluoroethyl ester of an aromatic sulfonic acid in molarproportions rangingfrom about 0.01:1 to about 1.5 :1 of the former withthe latter material. The preferred procedure is to add the ethylategradually to the ester so that the molar ratio of 1 :1 is not exceeded.

In a preferred embodiment of this invention a solution or dispersion ofmetal 2,2,2-trifluoroethylate containing up to about 40% by weight ofalcoholate in an inert liquid reaction medium is prepared by adding areactive metal to a slight molar excess of 2,2,2-trifluoroethanol withstirring at an elevated temperature below about 140 C. When the metal issubstantially reacted,

the solution or dispersion is slowly added to about a stoichiometricamount of a 2,2,2-trifluoroethyl ester of an aromatic sulfonic acidheated in a reactor at a temperature between 100 and 250" C. Crudebis(2,2,2 trifiuoroethyl) ether is evolvedfrorn the reaction mass,recovered, and purified by washing and distillation.

In an advantageous procedure for practicing my invention about 22 partsby weight of 2,2,2-trifluoroethanol in about 40 parts of dioxane arereacted with about 3 parts of metallic sodium above the-melting point ofthe sodium and below about 140 C. to form a solution of sodium2,2,2-trifluoroethylate. This solution is slowly added with stirring toabout 35 parts by weight of 2,2,2-trifiuoroethyl p-toluenesulfonateheated in a reactor at a temperature in the range 160185 C. The productboils otf from the reaction mass during the reaction. It is condensed,washed first with acid and then with dilute alkali, dried, and thebis(2,2,2-trifiuoroethyl) ether separated out by fractionaldistillation.

In practicing the method of this invention, it is preferred to add thesolution of metal 2,2,2-trifluoroethylate to the hot2,2,2-trifluoroethyl ester of the aromatic sulfonic acid.

The following example is presented for the purpose of illustrating theinvention, it being understood that the in- Example 23 parts of sodiummetal were placed in 300 parts of dry dioxane in. a reactor equippedwith an agitator and reflux condenser. The dioxane was heated to refluxwhile stirring. 150 parts of 2,2,2-trifiuoroethanol were added veryslowly in the period of about one hour, or until the sodium was allreacted, to form sodium 2,2,2-trifluoro ethylate. 250 parts of2,2,2-trifluoroethy1 p-toluenesulfonate prepared by reacting2,2,2-trifiuoroethanol with p-toluenesulfonyl chloride were placed inanother reactor and heated to about 160-185 C. The solution of sodium2,2,2-t1ifiuoroethylate in dioxane was added very slowly over a periodof about 1% hours. Bis(2,2,2-trifluoroethyl) ether formed continuouslyand distilled from the reactor with the dioxane into a cooled receivingvessel. The condensed eflluent from the reactor was fractionallydistilled, yielding 46.5 parts of products boiling at 55-73" C,

The crude product was washed successively with concentrated HCl, 62% Hconcentrated H SO and 5% NaOH solution. It was dehydrated over a dryingagent and then refractionated in a still. 20 parts of bis(2,2,2-trifiuoroethyl) ether were recovered (B.P. 62.5-63.5 C.

Analysis of the bis(2,2,2-trifluoroethyl) ether showed a molecularweight of 184 (calc. 182), and fluorine content of 62.9% (calc. 62.6%).The specific gravity was 1.3667. Refractive index was 1.2873 (daylight,25 G).

Since elemental analysis and the available spectral data cannotdistinguish positively between the symmetrical and unsymmetricalstructures possible, this compound was examined by nuclear magneticresonance technique and found to exhibit a spectrum which is consistentwith the symmetrical ether structure, (CF Cl-I O, showing it to bebis(2,2,2-trifluoroethyl) ether. M

The bis(2,2,2-trifiuoroethyl) ether was insoluble in water, butwas foundquite soluble or miscible in the ordinary organic solvents.

Following procedures substantially as described in the above example the2,2,2-trifluoroethylates of lithium,

potassium, calcium, barium, and strontium can each be reacted with anester of an aromatic or substituted-aromatic sulfonic acid having lessthan about 20 carbon atoms, for example with the 2,2,2-trifluoroethylester of benzene-, xylene-, naphthalene-, anthracene-, dodecylbenzene,or amylnaphthylenesulfonic acid, to produce bis(2,2,2-trifluoroethyl)ether.

The term bis(2,2,2-trifluoroethyl) ether has been used to describe thenovel fiuorinated alkyl ether of this invention. It is to be understood,however, that the ether can also be described as2,2,2,2',2',2'-hexafiuorodiethyl ether.

I claim:

1. Bis(2,2,2-trifiuoroethyl) ether, a liquid having a boiling point ofabout 63 C.

2. A process for the preparation of bis(2,2,2-trifluoroethyl) etherwhich comprises contacting a solution of metal fluoroalcoholate selectedfrom the group consisting of the 2,2,2-trifluoroethylates of lithium,sodium, potassium, barium, calcium and strontium in an organic solvent,said solvent selected from the group of organic liquids consisting ofdioxane, benzene, xylene, toluene, refined kerosene, and2,2,2-trifluoroethanol, with the 2,2,2-trifluoroethyl ester of anaromatic sulfonic acid having less than about 20 carbon atoms per acidmolecule, at a temperature of at least C., and recovering said ether.

3. A process for the preparation of bis(2,2,2-trifluoroethyl) etheraccording to claim 2 in which the metal fluoroalcoholate of2,2,2-trifluoroethanol is sodium 2,2,2- trifluoroethylate.

4. A process for the preparation of his (2,2,2-trifluoroethyl) etheraccording to claim 2 in which the 2,2,2- trifiuoroethyl ester of anaromatic sulfonic acid is 2,2,2- trifiuoroethyl p-toluenesulfonate.

5. A process which comprises reacting 2,2,2-trifluoroethyl p-toluenesulfonate with an alkali metal 2,2,2- trifluoroethanolate and obtaining2,2,2,2,2,2' hexafluorodiethyl ether as a product therefrom.

References Cited Henne et. al.: J'. Amer. Chem. Soc., vol. 72, pp. 4378-4380 (1950).

LEON ZITVER, Primary Examiner. H. MOORE, H. MARS, Assistant Framing r5,

